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Uneven-aged management options to promote forest resilience: effects of group selection and harvesting intensity The 9th IUFRO International Conference.

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Presentation on theme: "Uneven-aged management options to promote forest resilience: effects of group selection and harvesting intensity The 9th IUFRO International Conference."— Presentation transcript:

1 Uneven-aged management options to promote forest resilience: effects of group selection and harvesting intensity The 9th IUFRO International Conference on Uneven-aged Silviculture 17/06/2014 Presented by Guillaume LAGARRIGUES Co-authors : Valentine Lafond, Thomas Cordonnier, Benoît Courbaud National Research Institute of Science and Technology for Environment and Agriculture (IRSTEA) – Center of Grenoble With the collaboration of Andreas Zingg Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)

2 Adaptation of forest management to climate change Uncertainties about climate change consequences (Beniston et al. 2007) Precautionary approach: promote forest resilience by enhancing species diversity and uneven-aged structure (Puettman 2011 ; Seidl et al. 2011)

3 Managements options to promote forest resilience Create forest gaps by group selection Intensify harvesting Enhance natural regeneration Regenerate shade- intolerant species (Streit 2009) (Diaci and Firm 2011) Uneven-aged silviculture framework (Cordonnier et al. 2008)

4 Simulation experiments Forest dynamics simulation model Silviculture algorithmInitial state

5 Design of simulation experiments (Lafond et al. 2014) Stand area : 4ha ; Simulation period: 150 years, with cuts every 10 years 2 nd : harvesting intensification with individual selection 4 modalities of harvesting intensity 3 rd : harvesting intensification with group selection (500 m²) 4 modalities of harvesting intensity ILLUSTRATION 1 st experiment : spatialization of cuts Standard harvesting intensity 7 modalities of spatialization o Individual selection o Small groups (20 – 1 000m²) o One large gap at a time

6 Initial state Diameter class Abundance (trees / ha) 1905 Permanent plot located in the canton of Bern in Swiss, monitored by the WSL of Zürich

7 Samsara : an individual-based forest model

8 Model calibration for this study Diameter class Abundance (trees / ha) 1905 – Initial state Inverse modeling to calibrate the stand dynamics model so that model predictions fit to historical data (Lagarrigues et al., submitted) Observed data in 2009 Samsara Calibration of model parameters Predictions

9 Modeling natural regeneration Number of recruits % of full light Limitation by low light conditions Limitation by low density of seed bearers and competition with pioneer species Norway spruce Silver fir

10 Management modeling by a silviculture algorithm (Lafond et al. 2013) Ø h = 27,5 cm Ø (cm) N (t/ha) GhGh G max G standard G min G (m²/ha)

11 Results of the 1 st experiment (spatial aggregation of cut trees) Species mix (% of spruce basal area) Aggregation area (m²) Species balance Size diversity (Gini index) Uneven-aged Even-aged

12 2 nd experiment (harvesting intensity with individual selection) Species mix (% of spruce basal area) Proportion of potential harvesting (%) Size diversity (Gini index) Species balance Uneven-aged Even-aged

13 3 rd experiment (harvesting intensity with group selection) Species mix (% of spruce basal area) Proportion of potential harvesting (%) Species balance Size diversity (Gini index) Uneven-aged Even-aged

14 Management durability 1 st experiment2 nd experiment3 rd experiment Aggregation area (m²) Proportion of potential harvesting (%) Basal area (m²/ha)

15 Main conclusions and limitations Creating gaps and increasing harvesting intensity are both key management options to drive species mix and size diversity in spruce-fir stands Small-sized gaps (around 500m²) are sufficient to enhance natural regeneration, but large openings (> 1 000m²) may be necessary to increase proportion of shade-intolerant species such as spruce Harvesting intensity: trade-off between durability and spruce maintenance Group selection amplify harvesting intensity effects : forest management coupling both options should be applied with care Simulations are very sensitive to regeneration parameters (see Lafond et al. 2014; Courbaud et al., submitted) Regeneration response to light must be calibrated accurately Conclusions only valid in forest conditions close to those used for model calibration

16 Research perspectives with this silviculture algorithm Distinguishing thinning from harvesting operations Driving species mix directly by choosing the trees to harvest according to their species Driving forest stand structure and composition for biodiversity conservation Preserving rare species Sparing some very large trees Leaving more dead wood in stands => See poster session : Studying the response of timber production and biodiversity conservation to uneven-aged silviculture in mountain forests (Lafond et al.) Thinning potential Harvesting potential Harvesting diameter Thinning diameter

17 Funding and acknowledgments Guillaume Lagarrigues PhD The French Environment and Energy Management Agency (ADEME) The French National Forest Office (ONF) IRSTEA (Grenoble, France) Projects French research program “Biodiversity, Forest Management and Public Policy” (BGF) European Research project “Advanced multifunctional forest management in European mountain ranges” (ARANGE) Data for model calibration Swiss Federal Institute for Forest, Snow and Landscape Research (Zürich) Thank you for your attention !

18 References Beniston, M., Stephenson, D. B., Christensen, O. B., Ferro, C. A. T., Frei, C., Goyette, S., Halsnaes, K., Holt, T., Jylha, K., Koffi, B., Palutikof, J., Schoell, R., Semmler, T. & Woth, K. (2007). Future extreme events in European climate: an exploration of regional climate model projections. Climatic Change 81: Cordonnier, T., Courbaud, B., Berger, F. & Franc, A. (2008). Permanence of resilience and protection efficiency in mountain Norway spruce forest stands: A simulation study. Forest Ecology and Management 256(3): Courbaud, B., de Coligny, F. & Cordonnier, T. (2003). Simulating radiation distribution in a heterogeneous Norway spruce forest on a slope. Agricultural and Forest Meteorology 116(1-2): Courbaud, B., Goreaud, F., Dreyfus, P. & Bonnet, F. R. (2001). Evaluating thinning strategies using a tree distance dependent growth model: some examples based on the CAPSIS software uneven-aged spruce forests module. Forest Ecology and Management 145(1-2): Courbaud, B., Lafond, V., Lagarrigues, G., Cordonnier, T., Vieilledent, G. & De Coligny, F. (submitted). Critical steps to build and evaluate a mechanistic ecological model: a worked example with the Samsara.2 forest dynamics model. Ecological Modelling. Diaci, J. & Firm, D. (2011). Long-term dynamics of a mixed conifer stand in Slovenia managed with a farmer selection system. Forest Ecology and Management 262(6): Lafond, V., Lagarrigues, G., Cordonnier, T. & Courbaud, B. (2014). Uneven-aged management options to promote forest resilience for climate change adaptation: effects of group selection and harvesting intensity. Annals of Forest Science 71(2): Lagarrigues, G., Jabot, F., Lafond, V. & Courbaud, B. (Submitted). Approximate Bayesian Computation to recalibrate ecological models with large scale data: illustration with a forest simulation model. Ecological Modelling. Puettmann, K. J. (2011). Silvicultural Challenges and Options in the Context of Global Change: "Simple" Fixes and Opportunities for New Management Approaches. Journal of Forestry 109(6): Seidl, R., Rammer, W. & Lexer, M. J. (2011). Adaptation options to reduce climate change vulnerability of sustainable forest management in the Austrian Alps. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere 41(4):

19 Results of the 1 st experiment (Spatial aggregation of cut trees) Species mix (% of spruce basal area) Aggregation area (m²) Regeneration (Number of poles/ha) Species balance

20 2 nd experiment (harvesting intensity with individual selection) Species mix (% of spruce basal area) Aggregation area (m²) Regeneration (Number of poles/ha) Species balance

21 2 nd experiment (harvesting intensity with group selection) Species mix (% of spruce basal area) Aggregation area (m²) Regeneration (Number of poles/ha) Species balance

22 Thank you for your attention !

23 Individual selection (0 m²) Large gap (5000 m²  One large gap) …

24 Management modeling by a silviculture algorithm

25 Uneven-aged silviculture give managers many options to harvest wood while preserving forest resilience. Among them, we chose group selection and is favorably considered as forest gaps can enhance natural regeneration, especially for shade-intolerant species. Intensify harvesting is another interesting option that can allow reduce the amount of very large trees, reducing thus the risk of tree senescence and diseases while enhancing also natural regeneration by providing more light to the ground. However, such fine details about uneven- aged management have been poorly studied until now, and many questions remains about the efficiency of these options and the scales at which they should preferably applied.


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